CCR2 deficiency decreases intimal hyperplasia after arterial injury

Monocyte chemoattractant protein (MCP)-1 is upregulated in atherosclerotic plaques and in the media and intima of injured arteries. CC chemokine receptor 2 (CCR2) is the only known functional receptor for MCP-1. Mice deficient in MCP-1 or CCR2 have marked reductions in atherosclerosis. This study examines the effect of CCR2 deficiency in a murine model of femoral arterial injury. Four weeks after injury, arteries from CCR2^-/- mice showed a 61.4% reduction (P<0.01) in intimal area and a 62% reduction (P<0.05) in intima/media ratio when compared with CCR2^+/+ littermates. The response of CCR2^+/- mice was not significantly different from that of CCR2^+/+ mice. Five days after injury, the medial proliferation index, determined by bromodeoxyuridine incorporation, was decreased by 59.8% in CCR2^-/- mice when compared with CCR2^+/+ littermates (P<0.05). Although leukocytes rapidly adhered to the injured arterial surface, there was no significant macrophage infiltration in the arterial wall of either CCR2^-/- or CCR2^+/+ mice 5 and 28 days after injury. These results demonstrate that CCR2 plays an important role in mediating smooth muscle cell proliferation and intimal hyperplasia in a non-hyperlipidemic model of acute arterial injury. CCR2 may thus be an important target for inhibiting the response to acute arterial injury.